Congrats on the new car! Sounds like a good deal, too. With a commute of that length, you will probably do great in terms of FE, although hills can be killers.
I'm not a Prius driver, but it's pretty universal that one good way to deal with an incline is to let yourself slow down on the way up and let yourself speed up on the way down. This is called Driving With Load (DWL), and running a search on DWL in the forums ought to pull up lots of threads where people discussed it or even asked questions about it. In my HCH, I would use the assist, as sparingly as possible, on the way up and then let the battery charge back up on the way down (the next morning) by coasting as much as I can, but for an 07 Prius, there may be different/better ways. I'd say you should experiment with different speeds and acceleration until you find the most fuel-efficient way for you, on your particular route- use that instantaneous mpg feedback as much as you can to make your driving decisions, and you can't go too far wrong.
Welcome to GH!